Much effort in improving the performance of solar cells is allocated in finding methods to effectively trap the solar light, either by increasing the optical absorption or lowering the light losses. The light absorption can be improved by tailoring the band gap of semiconductors utilized in the solar cells. The loss of light usually occurs due to the light reflection from the materials used in a solar cell design. Methods known in the art that aim to decrease the light reflection use several approaches. A first method is related to anti-reflection coating and involves the mechanism of light interference, known in the art. Another method consists of making small cavities in the semiconductor for the purpose of trapping the light in those cavities by multiple light reflections (see, D. S. Ruby, S. H. Zaidi, S. Narayanan, “Plasma-Texturization for Multicrystalline Silicon Solar Cells,” 28th IEEE Photovoltaic Specialists Conference, Anchorage, USA, September 2000). Another method of trapping light within the solar cell employs diffuse light scattering (see, M. Vanecek, J. Springer, A. Poruba, et al., “Light Trapping and Optical Losses in Microcrystalline Si and Micromorph Solar Cell,” 3rd World Conf. on Photovoltaic Energy Conversion, Osaka, Japan, May 2003). In this method, the light reflects diffusely from the Silicon (Si) interface in all directions, rather than in a specular reflection direction. In this case, a part of the reflected light will undergo total reflection at a Si/TCO (transparent conductive oxide) interface and can be trapped within the TCO or Si. Thus, it is crucial according to this model that the Si/TCO is textured in such a way that it scatters the light diffusely. It is a common knowledge that the light can be scattered diffusely by a surface if that surface has an irregular texture, and the characteristic dimensions of the texture features are of the order or greater than the wavelength of light.
Surface texturing of single crystalline silicon has been previously obtained by creating randomly distributed pyramids by anisotropic wet etching; however, this approach will not work for multicrystalline thin film silicon (mc-Si) layers. Laser treatment, mechanical grinding, anodization, and photolithographic etching have been attempted to texturize mc-si films. However, all these methods are costly or not manufacturable in a large-scale production.